310-329 Eastern Emperors Gain Power Over Rome

This 20 year period  started with the Carnuntum Conference convened by the Eastern Roman Emperor Galerius pictured to restore order among those contending to be the western emperor. This conference was attended by Diocletian.

Maximian -- the Western emperor -- was forced to abdicate, and his son, Maxentius, was denied any status. A new emperor for the west was appointed - Licinius, a general - and Constantine remained as his co-ruler.

Maximian still yearned for power and was forced to commit suicide after an attempt to overthrow his son-in-law Constantine in 310.

To complicate matters, Galerius' co-ruler, Maximinus, resented the elevation of Licinius and to keep peace, Galerius made him his co-emperor.

In 311 Galerius died and Maximinus, implacably against the Christians, took over.

To secure his position, Constantine offered the marriage of his sister, Constantia, to Licinius, Emperor of the West.

Maximinus, Emperor of the East, promised Maxentius, living in Rome, the emperorship of the west, causing Constantine to invade Italy in 312. At the Battle of the Mulvian Bridge outside Rome Maxentius met Constantine (who used a Christian symbol on his shield) and Maxentius was defeated.

In the following year 313, while Licinius was in Rome marrying Constantine's sister, Maximinus marched across Asia Minor, taking Byzantium and crossed into Europe.

The armies of the east and west met, Maximinus fled, abandoning his army, and Licinius pursued him to Tarsus in Asia Minor, besieged him and finally he committed suicide.

Licinius kept his promise to Constantine about restoring church property taken by Maximinus, and was ruthless in eradicating all members - including women and children - of the families involved in persecuting Christians (far more ruthless than the previous emperors had been against members of the sect).

Amazingly, after Licinius had got rid of all of Constantine's rivals, and done much of his dirty work for him, Constantine then feared Licinius in his position as new Emperor of the East - with a male heir, Constantine's own nephew - and declared war on him in 316, got as far as Byzantium but was outsmarted by Licinius and retreated.

Previously sympathetic to Christians, Licinius now saw them as treacherous and protected himself by dismissing them from his service.

By 321 the empire was split, and wanting total control Constantine amassed a huge force and invaded Licinius's territory northwest of Thessalonica, northern Greece, and in 324 the two armies did battle. Licinius fell back and was finally defeated near Chalcedon. Licinius's life was spared when his wife (Constantine's sister) and the Bishop of Nicomedia interceded.

With Licinius's abdication, Constantine became the first emperor in 40 years to rule the empire on his own and immediately became embroiled in complicated Christian theological disputes, necessitating calling a Church Council in 325, held in Nicaea, attended by 300 bishops mainly from the east, though largely a Greek affair - its decisions were to be binding in the west as well and became known as the Nicene Creed.

As well as setting a fixed date for Easter, this council also eradicated Jewish customs from the service.